#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>

int main() {
    int n1, n2, n3, n4, n5;
    int total;
    double aver;
    scanf("%d %d %d %d %d", &n1, &n2, &n3, &n4, &n5);
    total = n1 + n2 + n3 + n4 + n5;
    aver = total / 5.0;
    printf("%.1lf", aver);
    return 0;
}